Recently, medical operation methods using light such as a laser, an intensed pulsed light (IPL), visible ray, infrared ray, and the like, have been rapidly spreading. For example, in the past, a medical operation method using light was mostly applied to a surgical operation, or the like, but recently, it is applied to various fields such as a plastic surgery, an operation for skin care, and the like.
In general, in order to oscillate a laser, laser oscillation medium is used. The laser oscillation medium may be made of, for example, Nd: YAG, Ruby, CO2, He, Ne, or the like, and may have a rod shape, or the like.
As an energy transmission device for exciting the laser oscillation medium, a high voltage/high current flash lamp charged with a discharge gas such as xenon, krypton, or the like, is commonly used, and an energy level of a laser generation can be obtained by exciting the laser generation medium by optical energy according to discharging of the flash lamp.
The size of the laser energy generated by the laser oscillation medium is dependent upon the size of the optical energy transferred from the flash lamp as an exciplex (or an excimer), and a period of time during which a laser is generated is also dependent upon an optical energy transfer period of the flash lamp.
Thus, in order to obtain a laser output having a certain size during a relatively long period of time, e.g., for tens of milliseconds (which is denoted simply by ‘mS’ in the present disclosure), the intensity of optical energy transferred from the flash lamp is required to be uniform, and in order to make the intensity of optical energy of the flash lamp discharged to the laser oscillation medium uniform, a current amount flowing through the flash lamp is required to be uniform.
FIG. 1 is a circuit diagram showing a configuration of the related art general flash lamp discharge driving apparatus, which briefly illustrates the configuration of the general flash lamp discharge driving apparatus disclosed in U.S. Pat. No. 5,620,478, for example, in FIG. 19, or the like. FIG. 2 is a graph showing current and voltage characteristics of an energy charging capacitor C illustrated in FIG. 1 when the energy charging capacitor C is discharged.
As shown in FIG. 1, when DC charge power is applied to the energy charging capacitor C, high level electric charges are charged and stored in the energy charging capacitor C. Thereafter, when the electric charges charged in the energy charging capacitor C are discharged to the flash lamp L, the flash lamp L is discharged and light is irradiated to a laser oscillation medium or a skin.
In this case, as shown in FIG. 2, a discharge current and the voltage of the energy charging capacitor C are reduced inverse-exponential functionally, and here, optical power discharged from the flash lamp L also has characteristics that it is reduced in a manner similar to that of the current/voltage characteristics illustrated in FIG. 2. Thus, when the flash lamp L is discharged by using the related art flash lamp discharge driving apparatus, since the output from the flash lamp L is inverse-exponential functionally reduced, resulting in a failure to generate optical power having a uniform size.
Thus, when uniform optical power is not generated from the flash lamp, in general, excessive energy is applied at an initial stage and dwindling energy is applied over the lapse of time. Thus, it is highly likely to irradiate a larger or smaller amount of laser than required to the affected part such as a patient's skin, or the like.
However, when an excessive amount of laser is irradiated to the affected part, a side effect such as a burn, or the like, may be generated, and conversely, if a smaller amount of laser is irradiated to the affected part, a treatment effect is insufficient. Thus, a technique of uniformly maintaining optical power of a laser for a particular period of time is urgently required.
Meanwhile, besides the method of generating and using a laser for a treatment by using a flash lamp and a laser oscillation medium as mentioned above, a medical treatment method using a device which is so-called IPL has been known.
The treatment method using IPL will be briefly described. Unlike the laser treatment method, a filter allowing only a particular wavelength to pass therethrough is provided near a flash lamp, and natural light such as visible light, infrared ray, ultraviolet ray, or the like, is allowed to pass through the filter so as to be directly irradiated to the skin for a treatment.
Like the treatment method using a laser, in the treatment method using IPL, the size of energy of light irradiated to the skin must be uniform, for which, thus, the current amount flowing through the flash lamp L must be uniform. In particular, in case of IPL, the flash lamp has characteristics in which a wavelength spectrum of emitted optical power is varied according to the size of a discharged current. Thus, when IPL is applied to a treatment method for which a particular wavelength is to be selected for the purpose of treating certain lesion, stable optical power is required.
Thus, when a surgical procedure is performed on the affected part such as a surface of a patient's skin, or the like, by using a laser, an IPL device, or the like, for a treatment, development of a basic technique of irradiating light of uniform optical power for a particular time is urgently required.